Last Updated on February 6, 2025
A dynamic compression plate is a metallic plate used for the internal fixation of bone typically after fractures. It is designed so that it applies dynamic pressure between the fragments to be fixed so that a better fracture contact is gained.
Dynamic plates are meant for the fixation of long bone fractures. They can also be used in periprosthetic fractures. The dynamic compression plates are available in stainless steel and titanium.
Types of Dynamic Compression Plates
A dynamic compression plate is available in many widths.
- Broad DCP: The broadest one is used to fix larger bones like the tibia, and femur whereas the less broad plate is used in case of forearm fractures. It uses screws of 4.5 mm. It is also called broad DCP.
- Narrow DCP: Another type with less width that also uses 4.5 screws is called narrow and is used in humerus.
- Small DCP: It is even smaller in width and is meant for forearm bones or fibula. It uses 3.5 mm screws.
- Mini plates: Used for metacarpals and phalanges. Use 2.7 or 2.0 mm screws.
A variant of dynamic compression plate, called DCP, low contact is more commonly used as this by its shape has minimum bone contact and thus preserves blood supply.
The under-surface of the DCP, by contact with bone, interferes with the blood supply of the underlying cortex.
Limited contact dynamic compression plate or LCDCP was an attempt to reduce the contact area because of its fluted undersurface.
The LCDCP has a fluted undersurface and minimizes the plate bone contact.
Principles of Dynamic Compression Plate Fixation
An effective plating should meet the following requirements.
- Appropriate width and thickness for the given bone
- Adequate and symmetric hold on either side of the fracture
- Must be closely apposed to the contour of the bone.
- Must neutralize all forces acting on the fracture i.e bending, compression, shear, and torque
Tension Band Principle
Bones are eccentrically loaded. That means one side is loaded more than the other. This affects to compressing one side and tendency to open the other side [compression and tension]. Hence when the plate is applied on the tension side, it turns the tension forces into compression forces bringing fracture fragments together provided the compression side is in contact too.
Image Credit: AO Foundation
Wherever possible plates should be put on the tension side of a fracture.
However, a plate may be positioned in compression Mode or neutralization mode. A plate in neutralization mode is just to counter bending,shear and rotational forces and not compression. The plate is used more like adjunct.
[Read about Plating Principles and Mode of Application]
Using a Dynamic Compression Plates in Forearm Fractures
Fractures of forearm bones [radius or ulna or both] require open reduction and internal fixation in most of adult cases. While the ulna is the subcutaneous bone which you can palpate from elbow to wrist, the radius is deep situated.
The radius can be approached either from the volar [on the side of the palm, Henry Approach] or from the dorsal [side opposite to the palm, Thompson approach] side.
In the proximal region [near to the elbow], the Thompson approach is preferred though it is ultimately the operating surgeon’s choice.
In the following images and text, I would take you through the dissection and fixation of a fracture of the proximal shaft of the radius which was opened using a dorsal approach and fixed with a dynamic compression plate. The patient also had an ulna fracture which was also fixed with DCP. The case in discussion is an adult male.
Preoperative X-ray
Following is the x-ray of the fractured forearm after injury and application of plaster splint. Both the bones are fractured and displaced. All displaced forearm fractures in adults require open reduction and internal fixation.
Preoperative Details
Skin incision over the proximal and middle thirds of the radius along a line drawn from the center of the dorsum of the wrist to a point 1.5 cm anterior to the lateral humeral epicondyle. It is called Thompson approach after the scientist who propagated it.
When the forearm is pronated, this line is nearly straight.
After the skin, the next layer is the fascia. Beneath that is a layer of muscles of the dorsal aspect. Interval for approaching the bone is developed between the extensor digitorum communis muscle and the extensor carpi radialis brevis, with each being retracted to the ulnar and radial sides.
In the proximal third of the forearm, the supinator muscle would be exposed. Here we have exposed the shaft of the radius after incising the distal part of the supinator muscle.
Careful dissection of this muscle would expose the deep branch of the radial nerve [posterior interosseous nerve]. The nerve is carefully retracted. The nerve is marked in the following diagram. Another method that does not involve exposure and retraction of the nerve is to lift the muscle free from the bone subperiosteally.
Fixation by compression plate and screws. The radial nerve is seen over the plate.
Following this fracture of the ulna was fixed with a dynamic compression plate as well.
Postoperative X-ray
Here is a postoperative x-ray. You will be able to appreciate the ulna fracture in this x-ray.
The fracture united well after 8 weeks of surgery.
References
- Basic Principles of Plating, 2025 https://surgeryreference.aofoundation.org/orthopedic-trauma/adult-trauma/basic-technique/basic-principles-of-plating#compression-plates (accessed Feb 06, 2025) [Link]
